The subject matter disclosed herein relates to occupancy detectors and, more particularly, occupancy detectors with managed communication traffic, reduced power consumption and improved occupancy determination.
Occupancy detectors, such as motion detectors, have been used for occupancy detection in many industries, such as the security and hospitality industries, for many years. In the hospitality industry, energy management systems have used motion detectors in the control of temperature setbacks or automatic lighting as a function of a presence determination of a person.
In hotel guestrooms, occupancy detection provided by motion detectors is also often augmented with a system that senses when a door to the room opens and closes. This is useful in applications where a person will not create any motion for a prolonged period of time, such as when sleeping in a bed or when visiting the bathroom and not being visible to the motion detector. In such cases, the system recognizes that the room door has closed recently but does not simply declare the room as being unoccupied just because no current motion is detected.
In these systems, when a door closure is sensed, the augmented occupancy detection system allows for a certain amount of time to pass (i.e., ten minutes) in which the room is assumed by the system to be occupied. Should motion be detected in that period of time, the system assumes that the room is occupied. If, after expiration of the period of time, no motion is detected, the room will be declared as being unoccupied. Afterwards, a guestroom control system can start to conserve energy in the room by setting back the temperature control, turning off lamps or by just informing the hotel staff at a management console that the room is no longer occupied. The room will now stay unoccupied at least until the next door opening or closing event has been detected. Once such an event is detected and the room is declared to be occupied, the system again waits for the door closure event and thereafter again attempts to declare the room as being unoccupied. However, in a case in which the room is declared unoccupied but a later motion signal is detected without a prior door opening, the system needs to recognize that the room was mistakenly declared unoccupied and subsequently declare the room as being occupied. In such a case, energy conservation methods are reversed and restored back to normal.
Typically, in the hospitality industry, motion detectors are wired to a controller that provides power to the motion detecting components, receives the motion signals, processes the door opening and closing events and determines the occupancy state of the room in a fashion similar to that which is described above. In addition, motion detectors are generally connected to a network to which the motion signals are sent as data packets at certain time intervals, which can be rather long to conserve power.
When such a controller senses a door closure event, the controller begins looking for occupancy signals. However, if the motion detector reports in a subsequent packet that there was motion detected but the detected motion actually occurred before the door closed, the motion detector may send the packet to the network as indicating that the room is occupied when it might not be.